The present invention relates to a method of manufacturing a panel assembly used to assemble a display panel and a transfer material sheet used to manufacture the panel assembly.
PDP (plasma display panel), a kind of display panel, has been getting widely used as display screens for television sets and monitors for computers since full color display was put into practical use. For further penetration, it is essential to develop a less expensive technique for manufacturing it.
An AC-type surface discharging PDP has been commercialized as a color display device. In the surface discharging system mentioned herein, light is maintained by making use of wall charge under AC drive and first main electrodes and second main electrodes which alternatively serve as positive electrodes or negative electrodes are arranged in parallel on an inner surface of one substrate of a pair of substrates. According to this system, a fluorescent layer for color display is provided on a second substrate facing a first substrate on which pairs of main electrodes are arranged. Accordingly, deterioration of the fluorescent layer caused by ion impact during discharge can be alleviated and the PDP can be long lived.
In the surface discharging PDP, the first and the second main electrodes extend along the line direction so that third electrodes for selecting columns and barrier ribs of about 100 to 200 xcexcm height for dividing discharge spaces by columns are required. The third electrodes are called as address electrodes and provided on the second substrate to reduce static capacity of cells. The barrier ribs prevent discharge coupling and color cross-talk between adjacent columns and define the size of the discharge space. Further, the fluorescent layer is preferably formed to cover not only surfaces parallel to a display screen but also sidewalls of the barrier ribs so that light emission area can be enlarged.
The PDP is completed through the steps of forming desired constituents such as electrodes on the first and the second substrates, coupling the substrates face to face to seal the circumference thereof (assembly step), cleaning the inside and sealing therein a discharge gas. In the manufacture of the display panel, a structure obtained by forming a layer of a predetermined pattern on a base substrate or processing the substrate itself to provide one or more constituent thereon is referred to as a xe2x80x9cpanel assemblyxe2x80x9d.
In a method of manufacturing the panel assembly according to the prior art, constituents are sequentially formed on the substrate. That is, one panel assembly is produced by forming the main electrodes, a dielectric layer and a protective layer in this order on the first electrode. Another panel assembly is produced by forming the address electrodes, the barrier ribs and the fluorescent layer in this order on the second substrate.
As methods of forming the barrier ribs, known are screen printing, sand blast technique, photolithography and additive method (also referred to as a lift-off technique or a burying technique). The screen printing is a method of performing repetitive printing of glass paste. The sand blast technique partially removes a uniformly applied paste by spraying a polishing material. The photolithography is to photolithographically pattern a photosensitive paste which has been uniformly applied. The additive technique is to provide a mask having a negative pattern of the barrier ribs, fill the glass paste in the openings of the mask and then remove the mask.
For the formation of the fluorescent layer, the screen printing has often been utilized since fluorescent substances of three colors, R, G and B, need to be arranged regularly. In short, three screens each having an opening pattern corresponding to the arrangement of the fluorescent substances of three colors are used to sequentially apply the fluorescent pastes one after another to spaces between the barrier ribs. Other techniques for patterning the layer include dispenser technique, as well as photolithography utilizing a photosensitive fluorescent paste. In either technique, three florescent pastes are individually applied, dried and then fired in one step.
The method according to the prior art requires an advanced alignment technique for ensuring precision in positional relationship among the address electrodes, the barrier ribs and the fluorescent layer. If their relative positions are mal-aligned, moirxc3xa and color displacement are resulted.
Further, costs of a material for forming the barrier ribs are expensive, which has been an obstacle to price reduction. In the screen printing, the screen is extremely exhausted because the printing is repeatedly performed in multiple times. In the sand blast technique, the greater part of a barrier rib material turns to be scraps. In the photolithography, about two third of the photosensitive paste layer will be etched away. Further, in the additive method, all the mask material for burying the paste will finally be removed. Moreover, for the formation of the fluorescent layer, serious problem remains in accuracy in screen printing (accuracy in plate) and plate life. Also in the photolithography, a method of collecting the photosensitive material is still problematic. Even if the problem concerning the precision is solved, it is extremely difficult to fill the layer material into a space in the shape of groove surrounded by the barrier ribs without including any air bubbles, so that a problem of low yields still remains.
Further, it requires a lot of formation steps and time, and is troublesome to frequently move the assembly during the formation steps.
The object of the present invention is to realize an alignment-free between the barrier ribs and the fluorescent layer and to minimize a waste of the barrier rib material for cost reduction. Another object is to realize an alignment-free among the electrodes, the barrier ribs and the fluorescent layer. Still another object is to sequentially manufacture a plurality of panel assemblies to reduce manufacturing time and steps per one panel assembly.
The manufacturing method according to the present invention is a method of manufacturing a panel assembly used to assemble a display panel having at least a plurality of barrier ribs that are belt-shaped in plan view for dividing the screen by columns, a plurality of electrodes for selecting the column, and a fluorescent layer that is belt-shaped in plan view extending along sidewalls of the barrier ribs and above the electrodes in each column provided on a substrate greater than a desired screen, the method comprising: forming a plurality of walls made of a fluorescent material that are belt-shaped in plan view so that the walls are arranged in stripes on a support body which is not the substrate; forming an electrode material layer on the walls; filling a barrier rib material in a space between the walls; coupling the substrate and the support body so that the barrier rib material faces the substrate; and transferring the walls, the electrode material layer and the barrier rib material to the substrate in one step, thereby to form the barrier ribs, the electrodes and the fluorescent layer.
According to the manufacturing method of the present invention, a layered body including the fluorescent material and the barrier rib material is formed into a pattern on the support body which is not the substrate, and then the layered body is transferred from the support body to the substrate in one step. In the layered body, the fluorescent material is formed into walls of a sufficient height and arranged in stripes, and the barrier rib material is arranged to fill the walls. Thus, the positional relationship between the fluorescent layer and the barrier ribs can be self-aligned. If the electrode material layer is provided on the walls of the fluorescent material before the barrier rib material is filled, the positional relationship among the electrodes, the fluorescent layer and the barrier ribs can be self-aligned.